The sun's activity is in free fall, according to a leading space physicist. But don't expect a little ice age. "Solar activity is declining very fast at the moment," Mike Lockwood, professor of space environmental physics at Reading University, UK, told New Scientist. "We estimate faster than at any time in the last 9300 years."

Lockwood and his colleagues are reassessing the chances of this decline continuing over decades to become the first "grand solar minimum" for four centuries. During a grand minimum the normal 11-year solar cycle is suppressed and the sun has virtually no sunspotsMovie Camera for several decades. This summer should have seen a peak in the number of sunspots, but it didn't happen.

Lockwood thinks there is now a 25 per cent chance of a repetition of the last grand minimum, the late 17th century Maunder Minimum, when there were no sunspots for 70 years. Two years ago, Lockwood put the chances of this happening at less than 10 per cent (Journal of Geophysical Research, DOI: 10.1029/2011JD017013).